1. Field of the Invention
The present invention relates to a measurement device for measuring various features, state quantities and the like of measurement targets such as liquids, gases or powders. More specifically, the present invention relates to a measurement device provided with an electrode mounting structure having an excellent sealing property.
2. Description of the Related Art
An electromagnetic flow meter configured to measure a flow rate of a liquid has been known as a conventional measurement device for measuring a physical quantity. The electromagnetic flow meter measures the flow rate by applying an electric current to a coil to generate a magnetic field inside a measurement pipe, then by picking up, with an electrode, an electromotive force generated in proportion to the electric conductivity of the liquid flowing inside the measurement pipe, and then by detecting the magnitude of the electromotive force. Generally, a resin lining formed of fluororesin, polyurethane resin or the like is applied to an internal surface of the measurement pipe of this electromagnetic flow meter in order to prevent corrosion.
The electrode used in this electromagnetic flow meter is in direct contact with a measurement target. In general, two types of structures are known as the structure of this electrode. These structures are called an external insertion type and an internal insertion type, respectively. In the external insertion type, an electrode is inserted into the inside of the container from the outside of the container in which a measurement target is to flow or be sealed. The electrode is pressed against the container from the outside by use of a spring and the like to ensure a sealing property of the container (see Japanese Patent Application Laid-Open Publications Nos. 2003-262544, 04-95719 and 2004-163193). In the internal insertion type, the electrode is inserted from the inside to the outside of a container, and the electrode is pulled outwardly from the outside of the container by use of a spring. In this way, an electrode head is closely attached to the container, and the sealing property of the container is thereby ensured (see Japanese Patent Application Laid-Open Publications Nos. 11-83569, 04-198816 (FIG. 2A), 2007-240231, 04-95819, and 03-55865).